Indonesia faces a drop in tourist numbers, at least in the short term, following Thursday's attack in central Jakarta claimed by Islamic State, in a blow to Southeast Asia's biggest economy already growing at its slowest pace since the financial crisis.

An Indonesian and a Canadian were killed, along with five attackers, while 20 people, including a Dutchman, were wounded. Two of the militants were taken alive, police said.

The attack could frustrate President Joko Widodo's ambitions to nearly double tourist arrivals to 20 million people by 2019, although Indonesia's tourism ministry said that it was sticking to that target despite the gun and bomb assault.

The government has removed visa requirements for visitors from 84 countries making a short visit, and is working to give visa-free entry to more nationalities in a bid to attract more travellers.

Indonesia, famous for the idyllic island of Bali, its dramatic volcanic landscapes and ancient temples, was estimated to have welcomed 10 million foreign tourists in 2015.

An Indonesian policeman carries a dog while patrolling at Thamrin business district in Jakarta, January 14, 2016.

Some travel agents said they had received calls from worried tourists, but they predicted that the effects of the attack would be shortlived.

"I think this incident will definitely have an impact on travel to Indonesia, especially to Jakarta," said Terence Cheong, director of Orient Travel and Tours, a travel agency based in Kuala Lumpur and the operator of MariMari.com, a hotel booking website.

In the Netherlands, whose tourists visit Bali for its beach resorts and other big islands for a taste of the country's colonial history, some travel agents received phone calls from concerned customers.

"It's early days, but I don't think it will be too bad," said Willem Linders, who operates roughly 200 group tours to Indonesia through his travel agency Indonesia Tours.

The number of Dutch visitors to Indonesia has jumped nearly 50 percent over the past decade from a low after the Bali bombings to more than 169,000 in 2014, according to the Indonesia statistics office.

Bali, located hundreds of miles from Jakarta and a major attraction for tourists, was a target of militant attacks more than a decade ago, when a nightclub bombing killed 202 people, most of them tourists.

Noviendi Makalam, spokesman for Indonesia's tourism ministry, expected tourist arrivals to the capital to drop over the next 2-3 months. He estimated that Jakarta contributed around 30 percent to the country's total foreign tourist arrivals.

Travel and tourism directly contributed around $23 billion to Indonesia's economy in 2014, or about 3.2 percent of GDP, according to a report from the World Travel & Tourism Council.

It forecast that figure to rise by 6 percent last year, and to show an annual growth of 5.3 percent from 2015-2025.